1. Field of the Invention
The present invention relates to a semiconductor apparatus including a semiconductor device mounted on a silicon substrate, and a method for manufacturing the semiconductor apparatus.
2. Description of the Related Art
As for the structure of the semiconductor apparatus including a semiconductor device mounted on a substrate, various types of them have been proposed such as disclosed in Japanese unexamined patents 2005-19609 or 2005-327820.
For example, when a silicon substrate is used for mounting a semiconductor device, micromachining on the substrate becomes possible. This enables a manufacturer to downsize a semiconductor apparatus. Further, silicon has higher thermal conductivity as compared with that of a sintered material such as ceramic. For this reason, there is an advantage of improving a heat radiation property under the situation such as mounting a device having relative large heat value, for instance, a light emitting device (LED). As the exemplified structure of a semiconductor device that is mounted on a silicon substrate, one of the known structures is a semiconductor device which is connected to a via plug penetrating through a substrate for mounting.
When the via plug is formed, first, a via hole (through hole) penetrating through a silicon substrate is formed, and then, an electrically conductive material is embedded in the via hole for its formation. The via hole is formed so as to penetrate through the silicon substrate in a cylindrical form by using, for example, a plasma (dry) etching technique.
However, when a via hole penetrating through a silicon substrate is formed, the defective shape (variation in shape) of the via hole may occur.
In general, such a defective shape is more likely to occur in the opening portion of the via hole. For example, performing the dry etching with using a mask pattern, problems of fine peeling, defective shape, or the like tend to occur at the interface between the silicon substrate and the mask pattern.
For this reason, various defective shapes of etching occur due to the problem of the mask pattern in the vicinity of the opening. In such a condition, in some cases, the cross sectional shape of the via hole is not formed in a circular shape in the vicinity of the opening. Further, a stress becomes more likely to concentrate to the opening portion of the via hole. This entails the fear that the damage (such as chipping or cracking) of the silicon substrate occurs.
Further, the occurrence of the defective shape of the via hole unfavorably deteriorates the reliability of the via plug.